app.post('/tosearcharound', multipartMiddleware, function (req, res) {

        var queryData = "";

        req.on('data', function (strChunk) {

            queryData += strChunk;

        });

        req.on('end', function () {

            console.log('数据接收完毕');

            //解析出客户端提交的信息中的参数，进行postgres查询

            var querystring = require("querystring");

            var params = querystring.parse(queryData);

            var pointx = params['pointx'],

                pointy = params['pointy'],

                searchRadius = params['searchRadius'];

            console.log(pointx+" "+pointy+" "+searchRadius);

            //利用客户端传过来的参数做查询，将查询结果返回到客户端

            //加载相应的模块，不同的数据库使用不同的模块

            var pg = require('pg');

            //构造连接数据库的连接字符串："tcp://用户名：密码@ip/相应点数据库名"

            var conString = "tcp://postgres:post@localhost:5432/projectdb";

            //构造一个数据库对象

            var client = new pg.Client(conString);

            //连接数据库，连接成功，执行回调函数

            client.connect(function (error, results) {

                if (error) {

                    console.log("could not connect to postgres" + error.message);

                    client.end();

                    return;

                }

                console.log("Client connect is ok.\n");

            });

            var querystring = "select st_astext(the_geom) from poi_beijing where ST_DWithin(ST_Transform(the_geom,26986),ST_Transform(ST_Geometryfromtext('point('||" + pointx + "||' ' ||" + pointy + "||')',4326),26986)," + searchRadius + ")";

            console.log(querystring);

            //执行相应点sql语句

            client.query(querystring, function (error, results) {

                console.log("in callback function.\n");

                //console.log(results);

                //console.log(results.rowCount);

                if (error) {

                    console.log("error");

                    console.log('GetData Error:' + error.message);

                    client.end();

                    return;

                }

                if (results.rowCount > 0) {

                    console.log(results);

                    //callback(results)

                    //指定为json格式输出

                    res.writeHead(200, {

                        "Content-Type": "application/json",

                        "Access-Control-Allow-Origin": "*"

                    });

                    //先将results字符串内容转化成json格式，然后响应到浏览器上

                    res.write(JSON.stringify(results, undefined, 3));

                    res.end();

                }

            });

        });

    }

);